||||||1|l||l|| ||| Illll "III 111] Ill III" "III ||l|| ||||| Illll III III” “II
`U3005563383A
`
`[19]
`United States Patent
`5,563,383
`[11] Patent Number:
`Cheng Oct. 8, 1996 [45] Date of Patent:
`
`
`
`
`
`[54] DYNAMIC CHANNEL MANAGENEENT AND
`SIGNALLING METHOD AND APPARATUS
`
`{76]
`
`Inventor: Alexander L. Chang, ll Sprindale
`Ave, White Plains, N.Y. 10604
`
`[21] Appl. No: 276,534
`
`[22] Filed:
`
`Jul. 18, 1994
`
`Int. CI.°
`{51]
`[52] U.S. C1.
`
`H04H 1104
`370173; 348112; 3101853;
`3701858; 45514.2; 45515.1
`34316. 9, 12, 13:
`[581 Field of Search
`45513.1, 4.2. 5.1, 6.1, 34.1; 379171, 73,
`76, 80, 85.3, 85.7, 35.8, 95.1, 95.2
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,513,206
`211986 Grauelctel. .......................... 455134.t
`5,132,680
`"111992 Teauka et a].
`.. 3701358
`5,224,119?
`...... 310135.11
`611993 Kaneshima
`
`5,331,316
`711994 Mestdagh ........... 370135.?
`
`5,355,375
`1011994 Christensen ..
`...... 370185.81
`
`3481112
`5.374352 1211994 Flohr ............
`
`343112
`5,434,611
`711995 Tarnurn
`
`Primary Examiner—Benedict V. Safourek
`
`[57]
`
`ABSTRACT
`
`services on a multiple access communication system, which
`comprises a central controller, a shared transmission media
`and a plurality of remote terminals dispersed throughout the
`network. The central controller comprises switch and con-
`1rol apparatus and a pool of transmitters and receivers. The
`communication channels between the central controller and
`remote terminals are arranged for signalling data and traffic
`bearer channels in the forward and reverse directions. The
`number of signalling data channels is adjusted to satisfy the
`trafiic requirements and for redundancy purposes. The for-
`ward and reverse signalling data channels are coupled in
`different mappings to support terminal grouping. Multiple
`access of the remote terminals for the upstream traffic are
`mitigated by separating remote terminals in groups via the
`channel allocalion and the terminal assignment process.
`Communication between the central controller and the
`remote terminals follows a multiple access scheme con—
`trolled by the central controller via polling procedure on
`each of the forward signalling data channels independently.
`In case of collision, the central controller engages the remote
`terminals in a selective polling process to resolve the con-
`tention. The overlapping polling method of the controlled
`access scheme increases the utilization of the signalling
`channel and reduces the time required to gain access to the
`shared transmission media. By dynamically adjusting the
`load on signalling data channels, the signalling process is
`greatly improved for efficiency and redundancy against
`anomalies with the added benefit of improved flexibility and
`extensibility. The system is especially useful in a two-way
`CATV network.
`
`There is Provided a dynamic and adaptable method and
`apparatus to support two—way mold-media communication
`
`20 Claims, 16 Drawing Sheets
`
`controller
`
`
`
`initialization
`
`response
`on RD-x‘
`
`
`
`EXHIBIT
`
`EX. 1001
`
`EX. 1001
`
`
` contention
`
`
`resolution
`
`selective
`poll
`
`Page 1 of 26
`Page 1 of 26
`
`PETITIONER'S EXHIBIT 1001
`
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 3, 1996
`
`Sheet 1 of 16
`
`5,563,883
`
`all switch
`remote
`
`terminals
`
`
`
`centralcontroller
`
`Page 2 of 26
`Page 2 of 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet2 of 16
`
`I
`
`5,563,883
`
`RD
`FD
`h—k
`
`1—1
`
`m
`
`J
`Figure
`
`3a
`
`FD
`n
`
`RD
`o
`
`p
`
`(1
`
`Figure
`
`3b
`
`RD
`it
`
`FD
`r
`
`3
`
`t
`Figure
`
`3c
`
`a
`
`polling
`
`controller
`
`initialization
`
`'
`
`clear all
`
`lists
`
`cycle
`
`tx.
`required YES
`
`response
`on RD-x'
`
`® @3133
`
`YES
`
`No
`
`contention
`
`
`
`terminal
`request
`
`selective
`poll
`
`Figure
`
`4
`
`Page 3 of 26
`Page 3 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct 8, 1996
`
`Sheet 3 of 16
`
`5,563,883
`
`
`
`tenninal
`
`response
`
`
`
`
`
`
`count
`
`
`exceeded
`
`
`terminal
`
`failure
`processing
`
`successful
`
`transmission
`
`
`
`
`
`
`Figure
`
`5
`
`Page 4 of 26
`Page 4 of 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 3, 1996
`
`Sheet4of 16 '
`
`5,563,883
`
`terminal
`
`request
`
`
`
`registration
`
`message
`
`
`
`reassign
`ment
`
`
`
`
`
`available
`capacity
`on other
`
`
`
`channel
`
`terminal
`
`disable
`
`
`
`allocate new
`
`channel
`
`
`
`terminal
`
`assignment
`
`Figure
`
`6
`
`Page 5 of 26
`Page 5 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`U.S. Patent
`
`Oct. 8, 1996
`
`Sheet 5 of 16
`
`5,563,883
`
`
`
`YES
`
`registration
`frame on RD—x
`
`toggle x
`between 12-‘2
`
`
`
`
`
`. YES
`
`
`
`
`
`
`
`
`terminal
`
`disable
`
`Channel
`
`
`
`
`
`assignment
`set x and x'
`
`Figure 7
`
`Page 6 of 26
`Page 6 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 6 of 16
`
`5,563,883
`
`
`
`controller
`
`poll or
`command
`
`tx.
`
`requn'ed
`
`collision or
`
`successful
`
` operation
`
` controller
`response
`
`
`transmission
`
`error retry
`
`
` terminal
`
`
`confirmation
`
`Page 7 of 26
`Page 7 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 7 or 16
`
`5,563,883
`
`Signalling data frame in the reverse
`Signalling data frame in the forward
`direction sent by remote terminals:
`direction sent by central controller:
`1
`1
`3
`1
`3
`1
`EE-_- HEB-—-
`
`bytes
`
`preamble (PMB)
`1- sequence to indicate the start of message frame transmission and aid detection of
`collision
`
`Terminal IDentifier (TID)
`-
`terminal identifier for command
`-
`lower TID of the range for the selective poll
`- 0 (hexadecimal 00) is an invalid TID used for disabling terminal during the
`registration process (SAT/SRT contains the serial number)
`' 255 (hex FF) for registration process (SAT/SRT contains the serial number)
`Signalling Action Type (SAT)
`serial number of the remote terminal for channel assignment during registration
`process
`selective poll including higher TID of the range (used also for general/Specific poll)
`selective poll with collision alert including higher range (used also for specific poll)
`in--coming call command on the indicated channel number
`release command
`disable command
`test command
`
`IIIIII
`
`- channel re-assignment command
`Signalling Request Type (SRT)
`serial number of the remote terminal for terminal registration process
`on--hook
`off— hook
`switch-hook
`
`ringing
`release
`
`IIIIIIIIIIII
`
`dial-digits
`incoming call blocking
`incoming call unblocking
`feature code (e.g., conference)
`test report
`alarm message (fault and fraud)
`multiple channel request (bandwidth-on-demand)
`- channelized services (sub-rate & multiple channels)
`Frame Check Sequence (FCS)
`. protection, which covers TID and SAT/SRT fields, against transmission error or
`collision
`
`Figure 9
`
`Page 8 of 26
`Page 8 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 3 of 16
`
`5,563,883
`
`1
`
`ranges of remote terminals
`
`N
`
`
`
`
`
`r31l
`
`r32
`
`1'33
`
`r34
`
`r35
`
`r36
`
`ievef of
`
`halving
`
`01h
`
`lst
`
`2nd
`
`3rd
`
`Figure
`
`10
`
`CO
`
`lines
`
`central
`
`remote
`
`controller
`
`terminals
`
` Figure 11
`
`119
`
`120
`
`122
`
`Page 9 of 26
`Page 9 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 3, 1996
`
`Sheet 9 of 16
`
`5,563,883
`
`
`
`
`
`
`
`first poll
`
`range r1 1
`
`
`
`NO response YES
`from r1 1
`
`range r12
`
`NO reSponse
`
`processing res—
`ponse from r11
`YES
`
`next poll
`range r21
`
`
` next poll
`
`
`
`
`
`
`
`
`
`tX. QITOI‘
` from r23
`
`pI‘OCGSSII'l y
` next poll
`
`continued in
`range 124 continued in
`
`
`
`
`Figure 12!)
`
`processing res-
`
`ponse from r12
`
`response YES
`
`. processing res—
`ponse from r21
`
`next p011
`range r31
`
`polling
`cycle
`
`Figure 12!)
`
`Figure 123.
`
`Page 10 of 26
`Page 10 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 10 of 16
`
`5,563,883
`
`fi'om
`Figure 12.5:
`
`from
`Figure 120
`
`
`
`
`
`
`next poll
`range 1'41
`
`
`
` response
`from r31
`
`response
`from [35
`
`Page 11 of 26
`Page 11 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 11 of 16.
`
`5,563,883
`
`time—-————p
`
`0.5T
`
`e
`
`5—
`a:
`9
`3:
`S
`u
`
`—I
`g
`r:
`3
`
`P
`
`\130
`132
`
`U)
`"a
`E
`a
`E
`H
`
`q.)
`2;
`E
`:-
`
`
`vzoiiozoz
`
`
`
`
`3*
`3
`f:-
`'=
`3
`
`I—
`E
`E
`8
`
`U)
`Ta
`.E
`E
`“
`3
`
`E
`E
`i".
`
`Flgure
`
`133
`
`Figure
`
`13b
`
`Page 12 of 26
`Page 12 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 12 of 16
`
`5,563,883
`
`
`
`first poll
`
`range r11
`
` tx. error
`
`processing
`
`polling
`cycle
`
`I‘D
`
`
`response
`
`from r1 1
`
`
`YES
`
`
`
`
`m
`
`next poll
`range r23
`
`YES
`
`
`YES
`
`
`NO response
`from r12
`polling
`Cycle
`
`
`
`a
`continued in
`Figure 14b
`
`processing res-
`ponse from :11
`
`next poll
`range r21
`
`polling
`16
`
`eye
`
`0
`continued in
`Figure 14b
`
`Figure
`
`143
`
`Page 13 of 26
`Page 13 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 3, 1996
`
`Sheet 13 of 16
`
`5,563,883
`
`from
`
`Figure Ha
`
`from
`
`Figure 14a
`
`
`first poll
`range r24
`
`
`
`
`
`
`
`nextpol a
`
`next p011
`range r35
`
`range r36
`
`Figure 14b
`
`Page 14 of 26
`Page 14 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 14 of 16‘
`
`5,563,883
`
`time
`
`l-t
`0
`=
`:3
`L.
`*a
`6
`U
`
`E
`h
`E
`a.)
`U
`
`m
`u—
`cc
`.5
`E
`:9
`u
`
`3
`c:
`E
`d)
`1-
`
`Figure
`
`15
`
`Page 15 of 26
`Page 15 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 8,1996
`
`Sheet 15 of 16
`
`5,563,883
`
`—-—-lm—IIII
`
`——->
`
`163
`
`
`
`
`
`167
`
`switching
`matrix
`
`
`
`
`
`
`16?
`168 167
`
`Page 16 of 26
`Page 16 0f 26
`
`PETITIONER'S EXHIBIT 1001
`
`PETITIONER'S EXHIBIT 1001
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 15 of 16
`
`5,563,883
`
`
`
`38
`
`
`t
`Isystem bus
`
`
`
`
`micro-
`
`processor
`
`
`
`14
`
`Page 17 of 26
`Page 17 0f 26
`
`PETITIONER'S EXHIBIT 1001
`PETITIONER'S EXHIBIT 1001
`
`

`

`5,563,883
`
`1
`DYNAMIC CHANNEL MANAGEMENT AND
`SIGNALLING NEETHOD AND APPARATUS
`
`FIELD OF THE INVENTION
`
`The present invention pertains generally to methods and
`apparatus for facilitating the two-way multi—media commu—
`nication based on a shared transmission media such as
`coaxial cable-TV network, and more specifically to methods
`and apparatus for signalling channel management and pro—
`tocol.
`
`BACKGROUND OF THE INVENTION
`
`A multiple access communication system comprises a
`central controller. a shared transmission media and a plu-
`rality of remote terminals dispersed geographically. To pro—
`vidc the means for multiple access is a classical problem in
`communication systems with a shared common transmission
`media. Some of the well known schemes are frequency
`division multiple access or FDMA, time division multiple
`access or TOMA, and code division multiple access or
`CDMA. These multiple access schemes deal with the tech—
`niques of separating the communication bandwidth into
`trafiic~bcaring channels. In a FDMA scheme, the commu—
`nication bandwidth is divided into the frequency bands. The
`TDMA scheme separates the communication bandwidth into
`time slots. The traffic is encoded and then decoded using
`difl‘erent code in a CDMA scheme.
`
`in all these multiple access schemes the contention for
`access is resolved through signalling protocols on a pre—
`determined and fixed signalling channel. There are propos-
`als to dynamically allocate traffic—bearing channels to meet
`the service requirements in terms of lower blocking prob-
`ability. However, in addition to availability, bandwidth and
`delay of the traffic-bearing channel, the traffic requirements
`should include responsiveness of the signalling process and
`the quality of the transmission means.
`The signalling protocols for multiple access communica—
`tion systems fall in two general categories for resolving the
`possible contention: scheduled access via polling or other
`means, and random access contention. In radiotelephony and
`local-area-network (CSMNCD) environment, the conten-
`tion is resolved by monitoring the signal during transmis-
`sion. which requires synchronization andl‘or means to moni-
`tor activities amongst all remote terminals and the central
`controller. 1n the CATV network, remote terminals have
`different distance from the central controller making syn-
`chronization difficult. It is also not feasible to detect colli-
`sion, i.e., multiple remote terminals transmit at the same
`time, on the CATV network since the remote terminals are
`attached to different branches of the network. The poll and
`response method is often used to schedule the multiple
`access from plurality of remote terminals, but it has the
`disadvantage of inefficiency due to wasteful interaction with
`remote terminals that are not in need of servicing.
`
`DESCRIPTION OF THE RELATED ART
`
`10
`
`15
`
`20
`
`30
`
`35
`
`40
`
`45
`
`SD
`
`55
`
`There are many proposals of means for dynamically
`adjusting the number of traffic-bearing channels according
`to varying traflic demands or the transmission quality in the
`radio telephony environment, e.g., U.S. Pat. Nos. 5,134,709,
`5,235,631 and 5,276,908. In addition U.S. Pat. No. 4,868.
`El] discusses the protocol over the common signalling
`channel for allocation of name—bearing channels. U.S. Pat.
`No. 4,870,408 proposes a process of re-assigning subscriber
`
`65
`
`2
`units to balance the traffic load over the available channels.
`U.S. Pat. No. 5,010,329 discloses a method for dynamically
`grouping terminals in blocks for which the central unit
`performs block polling on a common data channel. The
`present invention presents a method to dynamically allocate
`both signalling data and traflic-bearing channels and to
`dynamically assign remote terminals to these channels.
`The polling scheme is conunonly used to resolve conten-
`tion in a multiple access system. U.S. Pat. No. 4,385,314
`proposes a system to sequentially pull all terminals. Due to
`the inherent inefficiency with sequential polling method,
`some proposals with the following variations for perfor—
`mance improvement have been presented. U.S. Pat. No.
`4,754,426 proposes a two-level polling scheme with distrib-
`uted control. U.S. Pat. No. 4,829,297 proposes use of a high
`priority group. U.S. Pat. No. 4,868,816 proposes a binary
`polling scheme, similar to the polling scheme in the present
`invention, with terminal address in each poll. U.S. Pat. No.
`4,924,461 proposes a method to register other pending
`request on a second channel to interrupt sequential polling.
`U.S. Pat. No. 4,942,572 proposes a dual rate polling method
`using pseudo random sequence at high rate to poll all
`terminals resulting possibly in contention with a small
`number of terminals, and following the high rate poll by
`specific poll at lower rate in case of collision. This invention
`differs from the prior art in that multiple access is controlled
`through overlapping polling sequence executing on multiple
`channels in a parallel fashion. Only when collision occurs,
`this method will enter a selective polling sequence for
`contention resolution. The added benefit of this method is
`efficiency and redundancy against anomalies such as inter-
`ference and component failure.
`
`OBJECTS OF THE INVENTION
`
`To overcome the problems mentioned above, the objec-
`tive of the present invention is to present
`A flexible and extensible method for signalling channel
`management;
`A flexible and extensible method for assigning remote
`terminals to the signalling channels;
`An efficient asynchronous signalling protocol.
`In the present invention, a dynamic process is disclosed to
`adjust the number of signalling channels to meet the require-
`ments of varying traffic demand and the system growth. This
`is important in carrying multiamedia traffic with different
`requirements in both the traific~bearing channel bandwidth
`and the time required to setup a traffic—bearing channel. This
`dynamic signalling channel allocation and terminal assign-
`ment method also aids in system redundancy for anomalies
`such as interference and component failure. Integrated with
`the channel allocation and terminal assignment process, the
`present invention also presents an eflielent controlled mul-
`tiple access method. The central controller initiates the
`general polling on each signalling data channel in parallel to
`solicit request from all terminals assigned to die signalling
`data channel. Only when collision is detected, the central
`controller starts to poll selectively for resolution.
`Further objects and advantages of my invention will
`become apparent from considerations of the drawings and
`ensuing description thereof.
`
`BRIEF SUMMARY OF THE INVENTION
`
`The multiple access communication system architecture
`depicted in FIG. 1 comprises aplurality of remote terminals.
`a common shared transmission media, a central controller
`
`Page 18 of 26
`
`Pa 6 18 0f26
`
`PETITIONER'S EXHIBIT 1001
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`
`

`

`3
`
`4
`
`5,563,883
`
`and interface to wide area networks. There are provided a
`number of communication channels (L) to the wide area
`networks, a number of communication channels [M] for
`supporting a plurality of remote terminals (N). The M
`number of channels to support communication between the
`central controller and the remote terminals are separated into
`four categories as depicted in FIG. 2. for carrying signalling
`data and user traffic in the forward and reverse directions,
`i.e., forward signalling data or FD channel, forward traffic
`bearer or FB channel, reverse signalling data or RD channel,
`and reverse traflic bearer or RB channel. All communication
`signals between the central controller and the remote tenni-
`nals are multiplexed onto the shared transmission media.
`The remote terminals are equipment supporting the users’
`communication need and are distributed throughout the
`network. For simplicity reason,
`the summing device for
`signals from remote terminals are shown as a single device
`in FIG. 1. Each of the remote terminals has one RF data
`demodulator capable of receiving data on the assigned FD
`channel, one frequency agile receiver capable of tuning to
`the assigned FB channel, one RF data modulator capable of
`transmitting data on the assigned RD channel, and one
`frequency agile transmitter capable of tuning to the assigned
`RB channel. The central controller comprises a switch and
`control mechanism. and a pool of transmitters and receivers
`for the communication channels. The central controller
`provides concentration and control function to meet
`the
`communication demand of the remote terminals much the
`same way as a Private Automated Branch eXchange or
`PABX. The central controller also translates the signalling
`information according to the requirement of the network.
`There are two levels of concentrations provided with this
`system: contention in the shared transmission media via the
`signalling protocol. and through the switching matrix of the
`central controller:
`
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`The signalling channels are dynamically adjusted for
`efficiency and redundancy, This also adds to the extensibility
`of the system for the increasing traffic load and system
`growth. The downstream trafiic on these channels are schedw
`uled by the central controller. Multiple access of the remote
`terminals for the upstream traflic are mitigated by separating
`remote terminals in groups via the channel allocation and the
`terminal assignment process. Prompted by the remote ter—
`minals at startup. or through the failure recovery procedure.
`or deemed necessary by the central controller, the channel
`allocation and tem'tinal assignment process are initiated and
`controlled by the central controller. Through the registration
`process, the central controller assigns the remote terminal to
`a group supported by coupling of the specific forward and
`reverse signalling data channels. Afterwards, the communi-
`cation between the central controller and the remote termi—
`nals follows a two—phase process. The controlled multiple
`access method is used, on each forward signalling data
`channel in parallel, for sporadic user data transfer or sig-
`nalling purpose. The central controller either sends com-
`mand to a specific remote terminal or solicits requests via a
`general poll from remote terminals assigned to the forward
`signalling data channel. The remote terminals respond to the
`controller’s poll to request services. The selective polling
`process is used to identify the remote terminals involved in
`case of collision. The traffic bearer channel is used once the
`circuit is established via signalling protocol over the signal-
`ling data channels. The controlled multiple access scheme
`using overlapping polling method represents an efficient
`asynchronous signalling method and the decision process is
`designed to improve the effectiveness of the selective poll-
`ing coverage during the contention resolution process.
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`45
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`Accordingly the achieved benefits of the present invention
`are:
`
`General communication channels management architec-
`ture;
`
`Flexible and extensible scheme for signalling channel
`management;
`
`Flexible and extensible scheme for assigning remote
`tenninals to the signalling channels;
`Flexible and extensible scheme for supporting system
`growth and new services requirements;
`Improved system redundancy;
`Efficient asynchronous signalling protocol.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Other objects, features and advantages of the invention
`will be apparent from the following Description of the
`Preferred Embodiment taken together with the accompany-
`ing drawings in which:
`FIG. 1 is a illustration of a multiple access communication
`system architecture with interconnections between the
`remote terminals. the central controller which comprises the
`switch and control module and a number of transmitters and
`receivers. and the wide-area network.
`FIG. 2 shows the channelization of the communication
`bandwidth of the shared transmission media between the
`central controller and the remote terminals for different
`functions.
`
`FIG. 3 depicts the possible mappings of forward and
`reverse signalling data channels.
`FIG. 4 depicts the logic flow diagram for polling and
`registration process at the central controller.
`FIG. 5 depicts the logic flow diagram for command
`process at the central controller.
`FIG. 6 is the logic flow diagram for registration, terminal
`reassignment, channel allocation. and terminal assignment
`process at the central controller.
`FIG. 7 depicts the logic flow diagram for registration
`process at the remote terminals.
`
`FIG. 8 depicts the logic flow diagram for signalling
`process at the remote terminals.
`FIG. 9 details the message format for the signalling
`protocol between the central controller and the remote
`terminals.
`
`FIG. 10 shows the ranges of remote tenninals for selective
`polling during the contended resolution process.
`FIG. 11 is a message exchange diagram for signalling
`protocol between the central controller and the remote
`terminals illustrating a scenario of collision and its resolu—
`tion.
`
`FIG. 12 is the decision graph for contention resolution
`process using polling ranges as defined in FIG. 10 using the
`regular polling method.
`FIG. 13 contains signalling message exchange diagrams
`for comparison of two methods using the regular and the
`overlapping polling cycle.
`FIG. 14 is the decision graph for contention resolution
`process using polling ranges as defined in FIG. 10 using the
`overlapping polling method.
`FIG. 15 is a message exchange diagram using the over-
`lapping polling method for signalling protocol between the
`central controller and the remote terminals illustrating a
`scenario of collision and its resolution.
`
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`5,563,883
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`5
`
`FIG. 16 is the system block diagram of the central
`controller for supporting telephone services.
`FIG. 17 is the system block diagram of a remote terminal
`for supporting telephone services.
`
`DESCRIPTION OF PREFERRED EMBODIMENT
`
`The multiple access communication system architecture
`as depicted in FIG. 1 comprises a central controller 10, a
`shared transmission media 12. and plurality of remote ter-
`minals l4 dispersed geographically throughout the network.
`A pool of communication channels 16 (L) are provided to
`the wide area networks 18. a pool of communication chan-
`nels 20 (M) for supporting a plurality of remote terminals 14
`(N). The M number of channels to support communication
`between the central controller 10 and the remote terminals
`
`1.4 are separated into four categories for carrying signalling
`data and user traffic in the forward and reverse directions,
`i.c.. forward signalling data or FD channel 22, forward traffic
`bearer or F8 channel 24. reverse signalling data or RD
`channel 26, and reverse traific bearer or RB channel 28. All
`communication signals between the central controller ll] and
`the remote terminals 14 are multiplexed onto the shared
`transmission media 12. All remote terminals 14 are equip-
`ment supporting the users’ communication need and are
`distributed throughout the network. For simplicity reason,
`the summing device 30 for signals from remote terminals are
`shown as a single device in FIG. I. In a CATV network, this
`summing device 30 represents the splitters and taps con-
`necting the branches that make up the network.
`The central controller 10 comprises a SWitch and control
`' mechanism 32. and a pool of transmitters. called forward
`signalling data channel (FD) 22 and forward traffic bearer
`channel (FB) 24. and a pool of receivers, called reverse
`signalling data channel (RD) 26 and reverse traflic bearer
`channel (RB) 28. The central controller provides concentra—
`tion and control
`function to meet
`the communication
`demand of the remote terminals much the same way as a
`Private Automated Branch exchange or PABX. The central
`controller also translates the signalling information accord-
`ing to the requirement of the network. In addition to con-
`centration provided through the switching matrix of the
`central controller, contention in the shared transmission
`media via the signalling protocol provides another level of
`concentration with this system.
`Each of the remote terminals has one radio frequency
`(RF) agile data demodulator capable of receiving on the
`assigned FD channel 34, one RF agile receiver tuned to the
`assigned F'B channel 36, one RF agile data modulator
`capable of transmitting on the assigned RD channel 38, and
`one RF agile transmitter mned to the assigned RB channel
`40.
`
`Although the present invention is useful for inlet-working
`with a variety of difi’erent wide area networks, the telephone
`network will be used hereinafter to illustrate the present
`invention.
`
`As depicted in FIG. 2, the bandwidth is channelized for
`carrying traffic in the forward and the reverse direction. Data
`channels are used for carrying signalling or data tralfic while
`bearer channels are used for carrying user traffic similar to
`circuits in telephony. Therefore, there are altogether 4 types
`of channels as depicted in FIG. 2. FD-x is the signalling data
`channel in the forward direction 44, i.e., from the central
`controller to the remote terminals. numbered from 1
`to a
`FB-y is traffic bearer channel 46 in the forward direction
`numbered from 1 to b. RD-x’ is signalling data channel 48
`
`ID
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`in the reverse direction, i.e., from the remote terminals to the
`central controller, numbered from t to c. RB—y‘
`is ironic
`bearer channel 50 in the reverse direction numbered from 1
`to d. A guard band 42 is also shown to separate the signals
`traveling in the forward and the reverse directions if they are
`to be put side-by—side. As explained later a and c should be
`greater than or equal to 2 for redundancy reason. Note that
`if the channels are of equal size, then a+b and c+d shall
`remain constant if all channels are available free of inter—
`ference problem, i.c., there are a pool of channels from the
`central controller to the remote terminals, and a separate
`pool of channels from the remote terminals to the central
`controller. These pools are set aside for a flexible allocation
`scheme to be described in detail later.
`
`Although it is not necessary to have all channel to have
`equal bandwidth, the communication process can be man-
`aged more easily if the channels have simplified structure
`with equal bandwidth. In case of equal size of the FD and FE
`channels, the management scheme can relocare the FD to a
`channel that is better suited for data transmission while FB
`channel carrying normal voice communication can tolerate
`a considerable more noisy channel than FD channel is able
`10. Similarly, the management process can take advantage of
`the flexibility afforded by the equal size of the RD and RB
`channels. If the bandwidth of the communication channels
`to the wide area network is equivalent to the channels of the
`shared transmission media, the number L is less than or
`equal to the number M, which in turn is less than or equal
`to the number N. In case of channels with difi'crcnt sizes the
`central controller needs to have the additional intelligence
`for managing these channels eliicicntly, and to perform
`segmentation and reassembly. Note that conunurtication
`with asymmetric bandwidth requirement such as multi-cast
`can be elficiently supported in this system.
`The FB-y and RB-y' channels are allocated according to
`the signalling protocol communicated over the FD-x and
`RD-x‘ channels. Them is no contention in the forward
`direction, i.e., the traffic on each FD-x channel is scheduled
`independently. The number of signalling data channels are
`used to improve the efficiency servicing groups of remote
`terminals and the system redundancy. In case of transmis—
`sion failure (detected through a number of rabies without
`receiving acknowledgment), the central controller reverts
`back to FD-I and then FD—2 for transmission to the specific
`remote terminal. while the remote terminals reverts back to
`RD-l and then RD-2 for transmission and to FD-l and FD-2
`for reception. The FD-I and FD—Z channels are called
`primary forward signalling data channel and backup forward
`signalling data channel respectively. These RD—l and RD-2
`channels are called primary reverse signalling data channel
`and backup reverse signalling data channel respectively.
`With this general channelization architecture, a flexible
`management scheme is possible for channel arrangement
`and remote terminals grouping. For example, channel
`arrangement can be adjusted according to traflic pattern mix
`andlor more intelligent management scheme can be imple-
`mented with various priority lists. The channelization is
`shown to follow a FDMA scheme for ease of understanding,
`but this can also be easily adopted for TDMA or CDMA
`schemes.
`
`Multiple access of the remote terminals for the upstream
`traffic are mitigated by separating remote terminals in
`groups via the channel allocation and the terminal assign“
`ment process to be described later. The contention among
`remote terminals in each group is resolved through a con-
`trolled multiple access followed by selective polling in case
`of collision on each of the signalling data channel. The
`
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`number of remote terminals assigned to each of the RD
`channel is to be evenly distributed according to the traffic
`demand. In the case ofidentical traffic requirements from all
`users, the number of remote terminals assigned to each of
`the RD channel will be equal.
`The mapping of forward and reverse signalling data
`channels is under the control of the central controller
`dynamically. The mapping of pan (a) of FIG. 3 depicts the
`simplest arrangement with each pair of forward and reverse
`signalling data channels forming a terminal group. For
`example, the terminal group receiving on FD—h channel will
`transmit on RD—k. The part (b) depicts the one-to—many
`mapping where the central controller transmits on one FD-n
`channel while the remote terminals belonging to the same
`group respond in their assigned RD—o, RD—p, and RD—q
`channel respectively. In part (c) with the manynto-one map-
`ping shows that the central controller transmits on several
`FD (r, s and t) channels each reaching a subset of the group
`of the remote terminals, which respond in the same RD-u
`channel. Depending on the traffic pattern, some mapping
`will be more efficient in utilizing the bandwidth, e.g., the
`many-to-one mapping as depicted in part (b) of FIG. 3 is
`suitable for case where the traffic coming from the remote
`terminals far exceeds the traflic in the forward direction.
`Note that the mapping of part (0) can cause collision from
`remote terminals in different sub—sets of the same terminal
`group. This is the only mapping that will
`require the
`contention resolution process, described later, to be coordi-
`nated between multiple signalling data channels. Different
`types of mapping can be used at the same time (but not
`combined) for different segments of remote terminals when
`deemed appropriate by the central controller.
`Prompted by the remote terminals at startup. or through
`the failure recovery procedure, or deemed necessary by the
`central controller.
`the channel allocation and terminal
`assignment process is in